1. Field of the Invention
This invention relates to an integral composite material of silicone rubber and unsaturated polyester resin which is useful in the fields of electric and electronic equipment, business machines, automobiles and precision machines and a method for preparing the same.
2. Prior Art
A number of methods have been proposed for providing a bond between silicone rubber and organic resins. It is known, for example, to form a bond by applying a primer to a surface of molded resin, applying uncured silicone rubber thereto and curing the silicone rubber thereto or by curing self-adhesive silicone rubber compositions to molded resin. For the self-adhesive silicone rubber compositions, a number of proposals have been made on their tackifier component.
As another approach, it is known from Japanese Patent Publication (JP-B) No. 34311/1990 to add an organopolysiloxane containing at least 30 mol % of hydrogen atoms directly attached to silicon atoms to an organic resin whereby the resin is bondable with addition curing type silicone rubber. JP-B 45292/1988 discloses integration by physically fitting silicone rubber within molded organic resin. In Japanese Patent Application Kokai (JP-A) No. 183843/1988, a compound having an aliphatic unsaturated radical and a hydrolyzable radical attached to a silicon atom is grafted to an olefin resin and silicone rubber is bonded and integrated with the grafted olefin resin.
However, several problems arise with these prior art methods for integrating silicone rubber and thermosetting resin into a composite body. The primer method is cumbersome in that a once molded resin shape must be taken out of the mold before the primer can be applied thereto. The method of applying and curing a self-adhesive silicone rubber composition to molded resin has the serious problem that on molding the resin and silicone rubber using a mold, the silicone rubber itself adheres to the mold. In the method of adding hydrogensiloxane to organic resin, the properties of the resin itself can be altered by the addition of siloxane, rendering it difficult to obtain desired properties. The physical engagement method leaves a possibility that the two segments be disengaged by physical forces.
Currently, silicone rubber has found a spreading use in the fields of electric and electronic equipment, business machines, and automobiles because it is recognized to be highly reliable in the aspects of heat resistance, weatherability and electrical properties. To meet such a demand, there is a desire to have composite moldings in which thermosetting resin and silicone rubber are firmly united or bonded together.